Heater apparatus with controlled air and fuel intake

ABSTRACT

An engine pre-heater comprising a pair of concentric screens mounted in one end of a pear-shaped swirl chamber and forming a combustion chamber in which diesel fuel vapors are mixed with forced air delivered from a fan through the swirl chamber and from which oil residues are forced along a flow path extending to the other end of the swirl chamber to a drain.

United States Patent 91 Henchel HEATER APPARATUS WITH CONTROLLED AIR ANDFUEL INTAKE [75] Inventor: Herbert H. Henchel, Grosse Pointe,

Mich.

731 Assignee: Fltchefiiiii'chifiiifiiai' Industries, Ltd., Oshawa, H VOntariGICa'nada 22 Filed: Aug. 1, 1969 [21] App1.No.: 846,708

[52] US. Cl. 123/142.5 R, 60/63, 431/201, 431/20, 431/336, 431/352,431/121, 431/195 [51] Int. Cl. F02n 17/02, F23d 5/00, F2301 15/02 [58]Field of Search 123/1425; 60/63; 431/201, 20, 336, 352,121,195

[56] References Cited UNITED STATES PATENTS 795,409 7/1905 Nelson431/121 982,141 1/1911 Keclar 431/121 1,329,224 1/1920 Brazic 431/1952,357,454 9/1944 Brown 431/336 Oct. 16, 1973 2,602,495 7/1952 Green431/336 2,737,169 3/1956 Kimberlin 123/1425 3,072,176 1/1963 Sunday 1431/20 3,084,735 4/1963 Huston 3,158,192 11/1964 Mizer 3,234,928 2/1966Smith 3,400,700 9/1968 Lindsey et a1. 123/1425 FOREIGN PATENTS ORAPPLICATIONS 1,192,148 9/1959 France 431/336 Primary ExaminerLaurence M.Goodridge Assistant ExaminerRona1d B. Cox Attorney-Bruce G. Klaas [5 7ABSTRACT An engine pre-heater comprising a pair of concentric screensmounted in one end of a pear-shaped swirl chamber and forming acombustion chamber in which diesel fuel vapors are mixed with forced airdelivered from a fan through the swirl chamber and from which oilresidues are forced along a flow path extending to the other end of theswirl chamber to a drain.

21 Claims, 6 Drawing Figures SHEET 10F 3 PATENTEBUCI 161975 HEATERAPPARATUS WITH CONTROLLED AIR AND FUEL INTAKE BACKGROUND AND SUMMARY OFINVENTION This invention relates to an engine pre-heater for use withinternal combustion liquid-cooled engines (diesel or gasoline), whichare used by vehicles operating on the highways, off-the-roadearth-moving and stationary equipment. The function of the heater is topre-heat the engine coolant, making normal engine-starting possible incold weather. The engine pre-heater also eliminates the need forconventional engine warm-up periods during which engine efficiency isquite low and thereby acts as an anti-pollution control as well asreducing fuel costs. Furthermore, the pre-heater itself is extremelyclean burning and produces no substantial amounts of carbon or otherresidue. The invention involves improvements in heater apparatus of thetype disclosed in U.S. Pats. No. 3,072,176 and No. 3,234,928, thedisclosures of which are incorporated herein by reference.

While the pre-heater of the present invention may be used with othertypes of fuel (e.g., gasoline), one of the primary advantages of thepresent invention is the provision of engine pre-heater apparatus whichis able to vaporize any grade of diesel fuel and burn vaporized dieselfuel containing substantial amounts (e.g., 20 percent) of oil ordinarilyprovided in commercial diesel fuels for lubrication of engine cylinderwalls. It has been discovered that in order to successfully burn suchdiesel fuel, it is necessary to vaporize the liquid fuel and to separateand remove the oil. This oil, which those skilled in the art refer to asthe back-end, is heavier than the balance of the fuel and does not burnor vaporize. Therefore, means must be provided to separate and removethe oil to prevent accumulation in the heater apparatus in sufficientquantities to terminate combustion.

In order to more completely vaporize the liquid fuel, the burnerapparatus is arranged to concentrate the heat of combustion in the fuelburning area and to create turbulence in the burning area by use oftemperature differentials and shock waves and a high degree of molecularactivity. As a result, in the burning area, there is explosion-likeactivity indicating high energy molecular movement which causesvaporization and complete burning of all but the distillation residueback-ends which collect as residue on the bottom of the combustionchamber and which are constantly removed therefrom jacket heateroperation. jacket.

The pre-heater apparatus is associated with the engine cooling system ina new and improved manner' providing a thermosiphon system forcirculating the coolant through the engine water jacket. The heaterapparatus includes a vertically extending coolant jacket with a coolantoutlet at the top of the jacket located somewhat lower (e.g., at leastapproximately one-half inch) than the engine block coolant inlet andwith a coolant inlet at the bottom of the jacket. The system includesmeans to hold coolant in the coolant hacket to maximize heating of thecoolant by delaying the circulation of the coolant through the coolantja ket. In the preferred embodiment, the heater apparatus is formed as aself-contained portable unit which may be mounted closely adjacent theengine or spaced some distance therefrom.

The size, shape and position of the burner housing and combustionchamber apparatus is extremely important. The burner includes anelongated swirl chamber, having a somewhat pear-shape configuration inthe presently preferred embodiment, to which combustion air is deliveredunder pressure and caused to move therewithin in a particular flowpattern. To this end, a new and improved air delivery system is providedby the present invention.

The burner housing includes a fuel pot having a relatively small size inwhich a relatively small amount of fuel is maintained as compared withprior art devices. For example, approximately 20 cc of fuel are kept inthe heater fuel pot in the present invention, whereas fuel pots having acapacity of approximately 60 cc of fuel or more have been utilized inprior art devices. Furthermore, in the present invention, the fueldelivery system and the shut-off apparatus are arranged to maintain afull fuel pot both during and after heater operation. To this end, newand improved means of terminating heater operation are provided.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a somewhat schematic sideelevational view of illustrative apparatus embodying the principles ofthe invention;

FIG. 2 is another side elevational view of a portion of the apparatusshown in FIG. 1;

FIG. 3 is still another side elevational view of a portion of theapparatus shown in FIG. 1;

FIG. 4 is an exploded view, partly in section, of a portion of theapparatus shown in FIG. 1;

FIG. 5 is aperspective view in cross section of a portion of theapparatus taken generally along the line 5-5 in FIG. 2; and

FIG. 6 is a plan view of the apparatus shown in FIG. 4 taken along theline 6-6.

DETAILED DESCRIPTION Referring now to FIG. 1, in general, the pre-heaterapparatus is shown to comprise electrical means 10, an air deliverysystem 11, burner apparatus 12, chimneyheat exchanger apparatus 13,coolant jacket apparatus 14, a fuel system 15, and timer means 16, allof which are mounted on suitable support means 18. In the presentlypreferred arrangement, the pre-heater apparatus is enclosed as a unit ina metal case measuring l3 inches high by 10 inches wide by 7 34 inchesdeep with external connections for inlet and outlet hoses, battery andfuel pump wires. The pre-heater fuel system 15 comprises fuel pump means20, float bowl means 22, and shut-off valve means 24. The air systemcomprises a radially discharging impeller type blower fan means 26, FIG.3, restricted air inlet means 28, air inlet control valve means 30, airinlet control valve actuating means in the form of a solenoid 32, and anair delivery conduit means 34. The burner apparatus, FIG. 4, comprises aburner housing 36 on which chimney means 13 is mounted. Coolant heatingjacket apparatus 14 is mounted circumjacent the chimney means which isprovided with a suitable exhaust conduit.

Referring now to FIGS. 4-6, a swirl chamber 42 is provided within theburner housing 36 which comprises a box-like bottom member 43, which maybe in the form of an aluminum casting or the like, and a cover platemember 44. The burner housing is elongated and a downwardly dependingfuel pot 46 is provided in the bottom and adjacent one end thereof. Thelevel of fuel maintained in the pot is indicated by line 47. Acombustion chamber outlet opening 48 is provided in the cover plate 44directly above the fuel pot 46. Fuel residue outlet means 50, in theform of a removable threaded plug member having a flow passage extendingfrom the bottom of the burner housing to the bottom of the member, isprovided at the bottom of the other end of the burner housing oppositethe fuel pot. An air inlet means 52 extends into the burner housingthrough the top plate at the other end of the burner housing oppositethe fuel pot.

Fuel pot 46 is of generally cylindrical cross-section configuration,FIG. 6, and centrally spaced a substantial distance from the adjacentside wall 54 of the burner housing which is semi-cylindrical andconcentric with the center of the pot at 56. Side wall 57 of the otherend of the housing is also semi-cylindrical, but of small diameter thanside wall 54, and is connected to side wall 54 by side walls 58, 60which are outwardly diverging from the air inlet end of the housing tothe fuel pot end of the housing.

A combustion chamber 62 is provided by an outer burner screen 66 fixedlymounted in the outlet opening 48 in cover plate 44 and depending fromplate 44 into the burner housing above the fuel pot. Outer burner screen66 is formed of sheet metal or the like and extends upwardly through andin sealing association with cover plate 44. The outside diameter ofburner screen 66 is slightly less than the diameter of the top portionof the fuel pot and the bottom of the burner screen 66 is locatedslightly (e.g. one-sixteenth inch) below and inwardly of the bottom ofthe burner housing to provide a residue flow gap 67 therebetween. Screen66 is cylindrical and, in effect, except for the one-sixteenth inch gap,forms a continuation of the side wall 68 of pot 46 and defines thecombustion chamber 62 thereabove. A portion of the screen 66,intermediate the bottom surface 70 of the burner housing and the topsurface 72 of the cover plate, is perforated by a number ofsubstantially circular air inlet holes 74, evenly distributed inhorizontal and vertical rows. However, the top row of holes is spaced asubstantial distance from the bottom of surface 72 so that there is alength 76, FIG. 5, of imperforate screen providing a deflecting surfacefor inlet air and defining the only discharge path from the combustionchamber for the escaping gases and other products of combustion. Thebottom row of holes is also spaced above the bottom of surface 70 of theswirl chamber to provide a deflecting surface for the inlet air. In thepresently preferred embodiment, there are a total of 96 air inletopenings of approximately oneeighth inch diameter located withapproximately onefourth inch spacing between centers. Each opening isbelieved to act as a Venturi and create a kind of shockwave-explosiveeffect within the screen as relatively cool deflected swirling inlet airon the outside of the screen 66 enters the relatively hot combustionchamber 62 on the inside of the screen 66. As a result, the temperatureon the outside of the outer burner screen is substantially less than thetemperature on the inside thereof.

A stainless steel wire mesh type generally cylindrical inner burnerscreen 80 is concentrically mounted inside the outer burner screen andis supported by pinring means 82 on a seat 83. The bottom edge 84 of theinner screen is located substantially below the bottom edge 85 of theouter screen, FIG. 5, and below the fuel level line 47 so as to beimmersed in the fuel. The upper edge 86 of the inner screen terminatessomewhat less than one-half the distance between the bottom of thehousing and the bottom 72 of the cover plate so as to be located in theburner flame and to concentrate the heat of combustion in the top centerpart of the fuel in the fuel pot.

A fuel pot inlet 87, FIG. 4, is connected by a line 88 to shut-off valve24 and thence by a line 90 to the float bowl 22 and thence by a line 92to fuel pump 20 which is connected to a suitable fuel supply as shown inFIG. 1. The pre-heater operates independently from the associatedengine, but uses the same fuel as the engine obtained directly from themain fuel tank of the engine through a separate fuel pump and fuel line.The arrangement is such that the pot 46 is normally always filled withfuel at or about the level 47. When the preheater is turned off, as willbe more fully described herein, shut-off ,valve 30 is also closed tosmother the fire and trap a quantity of fuel in pot 46.

For purposes of starting the pre-heater, an electric fuel heater means94 is mounted in pot 46 to heat and vaporize the fuel therein untilsufficient heat is obtained for self-sustaining operation. A fueligniter means 96 is mounted on the burner housing 43 and extends througha slot 98 at the bottom of the outer screen 66 as shown in FIG. 5.

The combustion air delivery system is provided with flow control meansdesigned to promote particular flow characteristics in the burnerhousing. The flow control means includes vertical inlet conduit 28, theopening 97 to which is opened and shut by valve 30 upon actuation ofsolenoid 32. The size of the air inlet opening as defined by the spacebetween the valve 30 and the top of the conduit 28 in the open positionis adjusted to obtain the desired results in the combustion chamber. Theheater is turned off by closing the inlet opening and stopping thesupply of air which will snuff out the fire and leave the desired fuelsupply in the pot 46 rather than allowing the fire to burn out as inprior art devices.

The fan air inlet conduit 28 communicates with an inlet chamber 100mounted on the side of fan housing 102. Fan wheel means 26, in the formof a radial discharge squirrel cage impeller blade type, draws the airin centrally and axially from chamber 100 and discharges the airradially and circumferentially through an upwardly curved dischargeelbow 104 and into the discharge conduit 34. An electric fan motor 106is drivingly connected to the fan in a suitable manner. Conduit 34 issubstantially U-shaped in side elevation, FIG. 1, and includes anupwardly extending leg portion 108, a cross-over portion 110 and adownwardly extending leg portion 112. Vapor lock prevention means areprovided in the form of an air line 113 connecting air passage 112 tothe float bowl 22. The air inlet passages, openings and impeller fan arearranged to obtain a consistent smooth relatively non-turbulent air flowat the discharge opening 114, FIG. 4, of chute means 52.

The curvature and position of the discharge chute are such as to providea ring-like body of twisting incoming air generally directed toward theend wall 54 of the swirl chamber. Since the incoming alr stays along theinside surface of the discharge chute, the front surface 118 of thedischarge chute is positioned to direct the upper portion of the ring ofair toward the upper portion of the screen 66 above the upper row ofinlet holes and the bottom portion of the ring of air toward the bottomportion of the screen 66 below the bottom row of inlet holes. Thisarrangement prevents the incoming air from immediately escaping from theswirl chamber and creates the desired turbulence.

Air discharge chute means 52, FIG. 4, directs the air into the burnerhousing swirl chamber 42 in a particular manner and is placed within theswirl chamber in a particular manner for purposes to be hereinafterdescribed in detail. Referring again to FIG. 6, the discharge opening114 is centrally located between the adjacent side walls 58, 60 of thehousing and faces the burner pot 46 and screens 66, 80. The lower andrear surface 116, FIG. 4, of the discharge chute is formed on arelatively large radius to provide a relatively long smooth deflectionsurface. The front surface 118 of the discharge chute is slantedupwardly and away from the burner screens. In the presently preferredembodiment, the air discharge chute is mounted on the cover of the swirlchamber and held in place by a set screw (not shown) which permitsadjustment of the position of the discharge opening. The chute isgenerally cylindrical copper material and has a 1 A inch outsidediameter at the top and a l A inch inside diameter at the bottom. Theback of the chute at the cover is inch from the adjacent housing wall sothat the air can pass behind it. The top of the discharge opening 114 is1 inch from the outer screen 66 and the bottom is 1 inch from the outerscreen and one-sixteenth inch from the bottom of the housing. With theheater started and the fan means 26 blowing air through discharge chute52, the air in the swirl chamber 42 is believed to have a flow patterncomprising a central flow path of the ring of incoming air indicatedgenerally by arrows 125, 126 extending from the air discharge opening114 toward the outer burner screen 66, which causes the bottom and topportions of the ring of air to deflect therearound as indicated at 128,129 and against the far wall 54 of the swirl chamber as at 130 whichcauses the air to deflect 180 therearound as at 132, 133. The deflectedair is driven rearwardly along the sides of the swirl chamber as at 134,135, 136, 137 and onto the near wall 57 of the swirl chamber where theair is again deflected 180 as at 138, 139. As a result, there is aswirling mass of air turning and twisting in many directions (i.e.,turbulence), some of which is being forced through the air inletopenings 74 in the outer burner screen 66 to provide combustion air inthe combustion chamber 62. The turbulence prevents the intake air fromescaping too fast, resulting in holding adequate air to supply two atomsof oxygen to one atom of carbon liberated to form carbon dioxide (C0 Theair turbulence also counterbalances the electric motor R.P.M. drop dueto lower battery strength. Another result is that there is a stream ofair at the bottom of the swirl chamber moving first away from the firepot toward the near wall 54 and then along the sides of the swirlchamber toward the far wall 57 in the direction of arrows 134, 135, FIG.6.

In normal operation of the heater, the combustion chamber 62 is whitehot with the heat of combustion centrally concentrated in and around andabove the inner screen 80 which normally has a cherry red color and actsas heat transfer means maintaining a high temperature in the liquid fuelin the fuel pot and forming liquid particles and vapors that rise fromthe upper surface of the fuel. There is a substantial temperature andpressure differential along the inside and outside surfaces of the outerburner screen 66 which causes the swirling air to enter the combustionchamber at high velocity and to react in a kind of shock wave with therising particles and vapor to burst the particles and completelyvaporize the fuel in the combustion chamber. The swirl chamber dispersesthe relatively cold input air about the outer screen and the temperaturedifferential between the combustion chamber and the incoming air causesviolent motion of the fuel particles and vapors and agitates theremainder of the fuel in the fuel pot. As a result, some of the fuel inthe pot attains such high velocity that it bursts through the surfacefilm of the liquid fuel and escapes from the liquid as a gas. Some ofthe fuel is driven from the fuel surface in the form of small liquidparticles which are vaporized as they rise into the combustion chamber.The fuel and the products of combustion are driven and drawn into thechimney 13 through the outlet opening 48 at the top of the outsideburner screen, the swirl chamber 42 and combustion chamber 62 beingotherwise sealed to prevent any significant escape of air along anyother route.

In a pre-heater of this type, I have found that back end oil will not bevaporized and will float on the surface of the fuel and will eventuallychoke out the fire if not removed. The fuel oil back end cannot burn orvaporize because the boiling point required is higher than that obtainedin the pre-heater. During fuel vaporization, velocity action forces theback end to the surface of the pot. One of the main advantages of thepresent invention resides in the provision of residue removal means inthe form of a flow path extending along the bottom of the swirl chamberfrom the fuel pot to the bleeder means 50 whereat the back end residueis positively discharged from the burner housing. Velocity action in thepot pushes the residue into the pearshaped swirl chamber through gap 67against the near wall 54 where air turbulence forces it along the sidewalls 58, 60 to the rear wall 57. Unexpectedly, it has been found thatthe residual removal means appears to work most advantageously whenlocated some distance from the fire pot rather than closely adjacentthereto as might be ordinarily expected. In the illustrative form of theinvention, the flow path from the fuel pot to the bleeder means isprovided by gap 67 at the bottom of the outside burner and by the bottomsurface 70 of the burner housing along which the back end residue iscarried by the air in the swirl chamber in a path which extends from thefuel pot to the end wall 54 and then along the side walls 58, 60 to theend wall 57 where it.

accumulates about the bleeder means 50 and is removed by drainagetherethrough. Diametricallyopposed air holds the residue over thebleeder means where it drains free from the swirl chamber.

The hot exhaust gases are carried up the chimney 13 an over and around avertically adjustable heat exchange baffle means to an exhaust conduit41. Threaded adjustment means 151 permits necessary adjustment of thebottom of the baffle means relative to the flame which extends fromscreen 66. Coolant in jacket 14 is heated thereby and tends to rise fromthe coolant inlet 152 at the bottom of the jacket to the coolant outlet154 at the top of the jacket. A thermostat 155 is provided to sense thetemperature of the coolant and provide means to control the apparatus.The coolant jacket outlet 154 is connected by a line 156 throughrestrictor means 157 to the engine cooling system 158. A similarrestrictor means 159 is associated with the coolant inlet to controlflow of coolant through the coolant jacket. The restrictor means 157,159 act to delay passage of the coolant through the heater therebymaintaining higher coolant temperatures as well as higher heatertemperatures. The inlet 160 to the engine cooling system is locatedabout the coolant jacket outlet at an elevation sufficient to insure athermosiphoning effect, e.g., a distance of one-half inch in theillustrative embodiment. The engine cooling system is directly openlyconnected to the heater coolant jacket inlet 152 by a line 161 withoutany intervening valves or the like except for the restrictor means sothat the heater coolant jacket will be an integral part of the coolingsystem and effective immediately during start-up to cause a circulationof heated coolant through the cooling system.

In the presently preferred embodiment, the inside diameter of the inlet152 and outlet 154 are the same (i.e. one-half inch) but the outletrestrictor 157 is larger (e.g., seven-sixteenths ID) than the inletrestrictor 159 (e.g. three-eighths ID). The difference in restrictorsize helps prevent reverse flow as well as delay flow and increasepressure.

OPERATION The pre-heater of the present invention is particularlyadapted for use with engines used commercially in vehicles on andoff-the-road and stationary equipment which use pure anti-freeze insteadof water for coolant. Although ice may form whenever the ambienttemperature drops below +35 due to condensation inside the heatexchanger and burner housing, the ignition system on the pre-heateralways starts in the time allowed for ignition.

In operation, the heater may be automatically started by timer means 16or by a manually operable start-up switch (not shown) which causesimultaneous or successive energization of the fuel valve solenoid 162,the fuel pump 20, the pot heater means 94, the igniter means 96, the airvalve solenoid 32, and blower fan means 26 by suitable circuitry (notshown) associated with the vehicle electrical system and energizer orwith a separate electrical system and energizer. In the presentlypreferred arrangement, electric current for the heater is supplied bythe vehicle or engine battery. The current is required for the followingitems: electric motor for the fan, air valve solenoid, sump fuelshut-off valve solenoid, fuel pump, vibrator coil for energizing theigniter plug and the heating unit. The igniter plug and heater operatefor approximately 3 minutes at and for approximately five to six minutesat 20". The electric current consumption at -O is approximately 2.325(12v) and 1.162 (24v) ampere hours per hour. In any event, the potheater means 94 heats the fuel in the pot and causes fuel vapors to riseinto the combustion chamber 69 where they are ignited by the ignitermeans 96. After a few minutes operation, sufficient heat will have beengenerated to make the combustion process self-sustaining at which timethermostat means 155 may be employed to shut off the pot heater meansand the igniter means. At this time there is a continuous vaporizationand burning of the fuel in the pot. The level of the fuel is maintainedby the fuel system float bowl and combustion air is supplied underpressure as hereinbefore described. Coolant in the coolant jacket isheated and a thermosiphoning effect is begun with heated coolant risingfrom the coolant jacket outlet to the vehicle cooling system inlet andwith coolant flowing from the vehicle cooling system outlet to thecoolant jacket inlet. As the coolant circulates, the coolant isgradually heated until a substantially uniform vehicle cooling systemtemperature is reached. Then the heater apparatus is turned off eitherautomatically by thermostatic control or manually by de-energizing theair valve solenoid to close the air valve and smother the pot fire. Thefuel valve is also closed so as to trap a supply of fuel in the pot andthe fuel pump is de-activated. It will be understood that the exacttheory and/or manner of operation of the various components of thepre-heater may not be completely understood at this time and that theexplanation herein given is intended to be illustrative of the resultsobtained rather than an exact theory of operation.

The heater apparatus is associated with a thermosiphon system forcirculating the engine coolant through the cylinder block coolantjacket. The heater apparatus includes a 7 and /2 inch fire pot andcoolant jacket. It is made with a 2 and 4 inch I.D. inner tube and a 3and 4 inch O.D. outer tube. The coolant jacket is between these twotubes with a coolant capacity of one and onequarter pints. The coolantoutlet of the pre-heater needs only to be one-half inch lower than theengine block coolant inlet to obtain the thermosiphon function. Thepre-heater can be installed several feet away from the engine.

The pre-heater output temperature rise is from approximately 0 to +205in less than 10 minutes after ignition, and this temperature remainsconstant during the time required to heat the coolant in the engineblock jacket to normal operating temperature. The time required dependson the engine coolant jacket capacity (which can be, e.g., 4 to 8gallons) and the ambient air temperature, plus the velocity of the wind.

I claim:

1. A heater for an engine or the like comprising:

a fuel pot,

a combustion chamber formed above said fuel pot,

a closed swirl chamber having a side wall spaced from and surroundingsaid combustion chamber and said fuel pot,

forced air inlet means in said swirl chamber and spaced from saidcombustion chamber and said fuel pot and establishing a predeterminedpath of air flow to said combustion chamber including a path portionextending away from said fuel pot, and

fuel residue removal means in said swirl chamber and spaced from saidfuel pot and located in said path portion whereby fuel residue iscarried by the air flow along said path portion to said removal means.

2. The invention as defined in claim 1 and said fuel residue removalmeans being located closely adjacent said side wall beyond said forcedair inlet means opposite said fuel pot and said combustion chamber.

3. The invention as defined in claim 1 and said swirl chamber beingelongated and said fuel pot and said combustion chamber being located atone end of said swirl chamber and said air inlet means being located atthe other end of said swirl chamber.

4. An engine pro-heater comprising:

an elongated enclosed burner housing having a bottom wall, a top wall,and a side wall defining an air chamber,

a fuel pot at one end of said burner housing,

burner means at the one end of said housing defining a combustionchamber above said fuel pot,

air inlet passage means connected to said alr chamber at the other endof said burner housing,

fan means connected to said air inlet passage means to force air throughthe air chamber to the combustion chamber,

and said inlet passage means including a first vertically extendingportion connected to the atmosphere,

a second vertically extending portion spaced from said first verticallyextending portion and being of equal length and connected to the airchamber through said top wall of said burner housing, and

an intermediate cross-over portion therebetween and defining a generallyU-shaped flow path reducing turbulence of the air delivered to the airchamber.

5. The invention as defined in claim 4 and having a curved elbowconnected to said second vertically extending portion and extending intosaid burner housing and having a discharge opening facing said fuel potand burner means and directing the air toward the combustion chamber ina path generally transverse to the longitudinal axis of said fuel potand said combustion chamber.

6. An engine pre-heater comprising:

an elongated burner housing having top, bottom, and side walls and beingclosed except for an outlet opening for products of combustion in thetop wall at one end of the housing and an inlet opening for combustionair in the top wall at the other end of the housing,

a perforated outer cylindrical screen mounted in said outlet opening andextending into said burner housing and terminating closely adjacent thebottom of said burner housing,

a fuel pot located below said perforated cylindrical screen andconnected to a source of fuel,

a perforated inner cylindrical screen mounted in said fuel pot andextending upwardly within said perforated outer cylindrical screen andterminating below the top of said burner housing,

a combustion chamber defined by said perforated outer cylindrical screenand said perforated inner cylindrical screen,

fan means connected to said air inlet opening to cause a flow ofcombustion air from the atmosphere through the housing, and

an elbow type conduit connected to the inlet opening and extending intothe housing and directing combustion air from the one end of the housingto the other end of the housing onto and through said perforated outercylindrical screen and into said combustion chamber and creating a zoneof high molecular activity in the combustion chamber.

7. The invention as defined in claim 6 and the flow of air causing aflow of fuel residue from the fuel pot along the bottom of the burnerhousing, and residue removal means in said burner housing in the flowpath of the fuel residue and located in spaced relationship-to the fuelpot to receive and remove fuel residue from the fuel pot.

8. A heater adapted to burn a liquid fuel, such as diesel fuel, having aburnable constituent and an unburnable constituent during continuousself-sustaining operation and comprising:

pot means to hold a quantity of the liquid fuel with a free uppersurface maintained at a predetermined level within the pot means,

burner means extending upwardly from the pot means and defining acombustion chamber located above the pot means and the free uppersurface of the liquid fuel, heating means to heat and vaporize theburnable constituent of the fuel for delivery of fuel vapor to thecombustion chamber,

an air chamber surrounding said pot means and said burner means todelivery combustion air to said combustion chamber, and

drainage means located in said air chamber beyond said pot means tocontinuously drain the unburnable constituent during continuousself-sustaining operation.

9. The invention as defined in claim 8 and having air delivery means toestablish a flow path of air through said air chamber to said combustionchamber, said drainage means and said pot means being located in saidflow path whereby the unburnable constituent is carried by the air fromthe pot means to the drainag means.

10. The invention as defined in claim 9 and wherein said air chamberbeing elongated and comprising:

a first side wall portion being located relatively closely adjacent saidpot means,

a second side wall portion being spaced from said pot means a greaterdistance than and located opposite said first side wall portion, saidair delivery means extending into said chamber between said pot meansand said second side wall portion and having a discharge opening facingsaid pot means and said first side wall portion to establish an air flowextending from said pot means to said first side wall.

11. The invention as defined in claim 10 and said first side wallportion and said second side wall portion being arcuate and connected bygenerally tangentially extending side wall portions, said flow pathextending from said first side wall portion along said tangentiallyextending side wall portions.

12. The invention as defined in claim 11 and said drainage means beinglocated between said air delivery means and said second side wallportion.

13. The invention as defined in claim 12 and said drainage meanscomprising an opening in the bottom of said air chamber spaced inwardlyfrom said second wall portion and centrally located on a line extendingbetween the centers of the first wall portion and the second side wallportion.

14. The invention as defined in claim 13 and said air delivery meansbeing spaced inwardly from said second side wall portion to facilitateflow of air from said first side wall portion along said tangentiallyextending side wall portions to said second side wall portion.

15. The invention as defined in claim 14 and the flow path of air insaid air chamber being such as to establish a low pressure zone and tohold the unburnable constituent over said drainage means.

16. A heater adapted for continuous self-sustained burning of avaporizable liquid fuel comprising:

fuel pot means for holding a quantity of the liquid fuel,

burner means extending above said fuel pot means and defining acombustion chamber thereabove receiving vaporized fuel therefrom,

an elongated air chamber extending laterally from said burner means forsupplying air to said combustion chamber,

a first side wall portion of said air chamber being spaced closelyadjacent said fuel pot means and said burner means, a second side wallportion of said air chamber opposite said first side wall portion beinglocated more remotely from said fuel pot means and said burner meansthan said first side wall portion,

forced air supply means for supplying combustion air to said airchamber,

an air inlet conduit connected to said forced air supply means extendinginto said air chamber between said second side wall portion and saidfuel pot means and said burner means and having an air inlet openingfacing said first side wall portion and said fuel pot means and saidburner means and directing incoming combustion air theretoward.

17. The invention as defined in claim 16 and wherein said fuel pot meansand said burner means are generally cylindrical and are concentric, saidfirst side wall 12 portion being arcuate and concentric with said fuelpot means and said burner means.

18. The invention as defined in claim 17 and wherein said second sidewall portion being arcuate and connected to said first side wall portionby tangentially extending side wall portions.

19. The invention as defined in claim 18 and wherein said air inletconduit includes a cylindrical tubular portion extending parallel tosaid burner means and being concentric with said second side wallportion, an elbow portion curving toward said burner means, and anoutlet portion extending toward said burner means.

20. The invention as defined in claim 19 and said air inlet conduitbeing spaced inwardly from said second side wall portion to provide anair flow passage therebetween.

21. The invention as defined in claim 20 and having a fuel residuedrainage opening connected to said chamber and located between said airinlet conduit and said second side wall portion.

1. A heater for an engine or the like comprising: a fuel pot, acombustion chamber formed above said fuel pot, a closed swirl chamberhavIng a side wall spaced from and surrounding said combustion chamberand said fuel pot, forced air inlet means in said swirl chamber andspaced from said combustion chamber and said fuel pot and establishing apredetermined path of air flow to said combustion chamber including apath portion extending away from said fuel pot, and fuel residue removalmeans in said swirl chamber and spaced from said fuel pot and located insaid path portion whereby fuel residue is carried by the air flow alongsaid path portion to said removal means.
 2. The invention as defined inclaim 1 and said fuel residue removal means being located closelyadjacent said side wall beyond said forced air inlet means opposite saidfuel pot and said combustion chamber.
 3. The invention as defined inclaim 1 and said swirl chamber being elongated and said fuel pot andsaid combustion chamber being located at one end of said swirl chamberand said air inlet means being located at the other end of said swirlchamber.
 4. An engine pre-heater comprising: an elongated enclosedburner housing having a bottom wall, a top wall, and a side walldefining an air chamber, a fuel pot at one end of said burner housing,burner means at the one end of said housing defining a combustionchamber above said fuel pot, air inlet passage means connected to saidaIr chamber at the other end of said burner housing, fan means connectedto said air inlet passage means to force air through the air chamber tothe combustion chamber, and said inlet passage means including a firstvertically extending portion connected to the atmosphere, a secondvertically extending portion spaced from said first vertically extendingportion and being of equal length and connected to the air chamberthrough said top wall of said burner housing, and an intermediatecross-over portion therebetween and defining a generally U-shaped flowpath reducing turbulence of the air delivered to the air chamber.
 5. Theinvention as defined in claim 4 and having a curved elbow connected tosaid second vertically extending portion and extending into said burnerhousing and having a discharge opening facing said fuel pot and burnermeans and directing the air toward the combustion chamber in a pathgenerally transverse to the longitudinal axis of said fuel pot and saidcombustion chamber.
 6. An engine pre-heater comprising: an elongatedburner housing having top, bottom, and side walls and being closedexcept for an outlet opening for products of combustion in the top wallat one end of the housing and an inlet opening for combustion air in thetop wall at the other end of the housing, a perforated outer cylindricalscreen mounted in said outlet opening and extending into said burnerhousing and terminating closely adjacent the bottom of said burnerhousing, a fuel pot located below said perforated cylindrical screen andconnected to a source of fuel, a perforated inner cylindrical screenmounted in said fuel pot and extending upwardly within said perforatedouter cylindrical screen and terminating below the top of said burnerhousing, a combustion chamber defined by said perforated outercylindrical screen and said perforated inner cylindrical screen, fanmeans connected to said air inlet opening to cause a flow of combustionair from the atmosphere through the housing, and an elbow type conduitconnected to the inlet opening and extending into the housing anddirecting combustion air from the one end of the housing to the otherend of the housing onto and through said perforated outer cylindricalscreen and into said combustion chamber and creating a zone of highmolecular activity in the combustion chamber.
 7. The invention asdefined in claim 6 and the flow of air causing a flow of fuel residuefrom the fuel pot along the bottom of the burner housing, and residueremoval means in said burner housing in the flow path of the fuelresidue and located in spacEd relationship to the fuel pot to receiveand remove fuel residue from the fuel pot.
 8. A heater adapted to burn aliquid fuel, such as diesel fuel, having a burnable constituent and anunburnable constituent during continuous self-sustaining operation andcomprising: pot means to hold a quantity of the liquid fuel with a freeupper surface maintained at a predetermined level within the pot means,burner means extending upwardly from the pot means and defining acombustion chamber located above the pot means and the free uppersurface of the liquid fuel, heating means to heat and vaporize theburnable constituent of the fuel for delivery of fuel vapor to thecombustion chamber, an air chamber surrounding said pot means and saidburner means to delivery combustion air to said combustion chamber, anddrainage means located in said air chamber beyond said pot means tocontinuously drain the unburnable constituent during continuousself-sustaining operation.
 9. The invention as defined in claim 8 andhaving air delivery means to establish a flow path of air through saidair chamber to said combustion chamber, said drainage means and said potmeans being located in said flow path whereby the unburnable constituentis carried by the air from the pot means to the drainage means.
 10. Theinvention as defined in claim 9 and wherein said air chamber beingelongated and comprising: a first side wall portion being locatedrelatively closely adjacent said pot means, a second side wall portionbeing spaced from said pot means a greater distance than and locatedopposite said first side wall portion, said air delivery means extendinginto said chamber between said pot means and said second side wallportion and having a discharge opening facing said pot means and saidfirst side wall portion to establish an air flow extending from said potmeans to said first side wall.
 11. The invention as defined in claim 10and said first side wall portion and said second side wall portion beingarcuate and connected by generally tangentially extending side wallportions, said flow path extending from said first side wall portionalong said tangentially extending side wall portions.
 12. The inventionas defined in claim 11 and said drainage means being located betweensaid air delivery means and said second side wall portion.
 13. Theinvention as defined in claim 12 and said drainage means comprising anopening in the bottom of said air chamber spaced inwardly from saidsecond wall portion and centrally located on a line extending betweenthe centers of the first wall portion and the second side wall portion.14. The invention as defined in claim 13 and said air delivery meansbeing spaced inwardly from said second side wall portion to facilitateflow of air from said first side wall portion along said tangentiallyextending side wall portions to said second side wall portion.
 15. Theinvention as defined in claim 14 and the flow path of air in said airchamber being such as to establish a low pressure zone and to hold theunburnable constituent over said drainage means.
 16. A heater adaptedfor continuous self-sustained burning of a vaporizable liquid fuelcomprising: fuel pot means for holding a quantity of the liquid fuel,burner means extending above said fuel pot means and defining acombustion chamber thereabove receiving vaporized fuel therefrom, anelongated air chamber extending laterally from said burner means forsupplying air to said combustion chamber, a first side wall portion ofsaid air chamber being spaced closely adjacent said fuel pot means andsaid burner means, a second side wall portion of said air chamberopposite said first side wall portion being located more remotely fromsaid fuel pot means and said burner means than said first side wallportion, forced air supply means for supplying combustion air to saidair chamber, an air inlet conduit connected to said forced air supplymeans extending into said air chamber between said second side wallportion and said fuel pot means and said burner means and having an airinlet opening facing said first side wall portion and said fuel potmeans and said burner means and directing incoming combustion airtheretoward.
 17. The invention as defined in claim 16 and wherein saidfuel pot means and said burner means are generally cylindrical and areconcentric, said first side wall portion being arcuate and concentricwith said fuel pot means and said burner means.
 18. The invention asdefined in claim 17 and wherein said second side wall portion beingarcuate and connected to said first side wall portion by tangentiallyextending side wall portions.
 19. The invention as defined in claim 18and wherein said air inlet conduit includes a cylindrical tubularportion extending parallel to said burner means and being concentricwith said second side wall portion, an elbow portion curving toward saidburner means, and an outlet portion extending toward said burner means.20. The invention as defined in claim 19 and said air inlet conduitbeing spaced inwardly from said second side wall portion to provide anair flow passage therebetween.
 21. The invention as defined in claim 20and having a fuel residue drainage opening connected to said chamber andlocated between said air inlet conduit and said second side wallportion.